1. Field of Invention
The present invention relates to a method for fabricating a semiconductor device. More particularly, the present invention relates to a method for fabricating a metaloxide semiconductor (MOS) transistor.
2. Description of Related Art
In a conventional method of forming a metal-oxide semiconductor (MOS) transistor, an oxide layer is commonly formed to cover and electrically isolate the MOS transistor. The dielectric constant of oxide is approximately 3.8 to 4.0. As the device dimensions reduce in size and the transmission speed increases, the oxide layer does not satisfactorily provide electrical isolation, because using the oxide layer for electrical isolation causes a serious gate-to-drain capacitance between the gate and the source/drain region. Thus, the performance of the device is affected.